WPMU DEV on "Adding a theme, error recieved"

Hi @HafsaTM,

I hope you are well today and thank you for your question.

Internal server error is not specific to WordPress, and it can happen with anything else running on your server as well.

Perform the instructions provided on this page http://wpmu.org/ten-of-the-most-common-wordpress-problems-and-their-solutions/ in the section 1. 500 Internal Server Error

You can also try uploading theme using FTP in wp-content/themes/ folder and activate it from Admin -> Appearance -> Themes from the back end.

Best Regards,